Precision weighing technology demands increasingly high measurement resolution and precision, while at the same time requiring that balances handle ever-broadening measurement ranges. Thus, products with markedly differing weights and spatial dimensions are to be weighed in continuous operation, sometimes at very high transport speeds.
Monolithically constructed weighing cells with integrated lever transmissions operating according to the principle of electrodynamic force compensation are known for use in precision balances. Such systems with single transmission are usable only up to a weight of roughly 30 kg. To extend the measurement range, a stronger magnet system can be chosen, along with the associated high costs, or the transmission ratio of the lever mechanism can be increased. In the case of multiple transmissions, however, the resolution of the measurement system that can be picked up at the final lever decreases. Moreover, the production of monolithic multiple transmissions is technically elaborate and often not possible at all, due to the small amount of installation space available.
Also, the parallel rod connections between the stationary bases and the load receptors usually provided for monolithic weighing cells cannot be used due to their low load-bearing capacity. The torques that act on the parallel rod construction in the case of an eccentric load on the load receptor are particularly difficult to manage and negatively influence the accuracy of the balance. A spatial enlargement of the parallel rod construction is expensive and increases the difficulty of producing undercuts between the parallel rods, which must be wider in this case.
What is needed is a way to provide a precision balance in order to be able to weigh materials having a wide variety of different weights and dimensions with high resolution and measurement precision, with simultaneous insensitivity to torques.